Guys, I'm trying to make a spreadsheet of what flywheel/flexplate will work with what engine, starter, etc, etc. This is FAR more complicated that I thought it would be. Usually with my engines I know what is supposed to be on it and that's what I use. Doing swaps not knowing what block or flywheel/flexplate it originally came with gets complicated in a hurry. Need a little help.

Throw out the 400 for now. I know all about the 400. It's my engine of choice and it uses an unbalanced 168 tooth flywheel/flexplate. No biggie.

Let's talk early model (two piece main) 305s and 350s versus late model (one piece main) 305s and 350s.........

ALL late model 305s and 350s use 153 tooth flywheels/flexplates and I know they are MILDLY unbalanced units. Not as severe as a 400, but unbalanced nonetheless.

Early model 350s and 305s could be either 153 tooth OR 168 tooth. Most 350s were 168 tooth and all (?) 305s were 153 tooth. They were truly neutral balanced units in either case and they can't bolt to a one piece rear man block regardless. Yes? No?

OK, now the post-gradulate level questions...........

If you have an early model engine that uses the 153 tooth flywheel is it the BLOCK that's different from a 168 tooth setup or the STARTER? The spur gear on the starter HAS TO sit closer to the hub to make up for the smaller diameter of the 153 tooth flywheel/flexplate. I believe the block's different but I don't know that for sure.

Are starters different between early model blocks and late model?

Are starters different between 168 and 153 tooth setups?

What interchange possibilities are there, even if you throw out the unbalanced versus neutral balance isuues and the fact that you can't exhange flywheels/flexplates between early model and late model blocks? I'm trying to nail down what's the key difference between a 168 tooth setup versus a 153 and if the difference apply from early to late model engines.

 

Damon- I wish your questions were numbered! I think I might know some of the answers (for a change!!).

 

do you have a lot of free time? 1)- 2 piece rear main block takes flywheels and flexplates designed for a 2 piece crankshafts 153-168t. 2)-1 piece rear main block takes fly and flex designed for 1 piece cranks. i.d.'d by a small 3 inch diameter bolt pattern on a circular end. 95% of all single piece cranks came with small fly or flex. 3)-small starter=straight across, large starter= staggered, unless the jap starters are considered-that design is straight across for both its a matter of picking the pair of straight across mount holes for the size flywheel. 4)- you can run a one piece crank in a 2 piece block with an adapter. 5)-any good balance shop will be able to balance match any combo of the above types including the 400. make a 350 305 internal whatever into a 400 external(any size-153\168) as long as the fly flex bolts to the crankshaft you be in fat city. can i stop typing now? ok good. thanks,seeya

 

OK, let's make this simpler. Let's make it a single question (in 37 different parts ).

What's the difference between a 168 and a 153 tooth application, besides the flywheel/flexplate itself? Is the block drilled so the starter is in such a position as to only work with one size flywheel/flexplate (i.e. it's a "153 tooth block" or a "168 tooth block.") Or is the starter itself different between 153 and 168 tooth applications?

Stated another way.... The spur gear on the starter must sit closer to the crank to engage on a 153 tooth flywheel/flexplate than on a 168. So what makes that difference? The starter itself or the location of the starter where it bolts to the block?

I am fairly sure it's the block, but I want to be certain. Thanks in advance. No, no real spare time, just got a bug up my butt about this.

 

sbc engine blocks (majority of-for the sake of this discussion)are drilled with 2 sets of holes on the oil pan rail to mount the starter. the "straight across" pattern accepts the starter motor for the small flywheel. the 2nd set of holes in the pan rail is the "staggered" variety and that staggered style of starter motor is for the big flywheel. BUTTTT-when utilizing a typical "mini" starter-usually manufactured by our trading "partners"in the land of the rising sun the starter itself also has 2 sets of holes on its mounting block and it bolts to the "straight across" small pattern for both big and small flywheels

 

Thanks, Grump, that was what I was trying to nail down. This is one of those subjects where I know every exception to the rule but not the rule itself.